- Email: [email protected]
Measurement of Small Complex Shapes
ScienceDirect Transportation Research Procedia 00 (2019) 000–000 ScienceDirect Available online at www.sciencedirect.com
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Transportation Research Procedia 00 (2019) 000–000
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Transportation Research Procedia 40 (2019) 251–258 www.elsevier.com/locate/procedia 13th International Scientific Conference on Sustainable, Modern and Safe Transport (TRANSCOM 2019), High Tatras, Novy Smokovec – Grand Hotel Bellevue, 13th International Scientific Conference Sustainable, Modern and Safe Transport Slovak Republic,on May 29-31, 2019 (TRANSCOM 2019), High Tatras, Novy Smokovec – Grand Hotel Bellevue, Slovak Republic, MayComplex 29-31, 2019 Shapes Measurement of Small
* Measurement ofRobert SmallČep Complex Shapes Radek Hruby, Lenka Cepova, , Ondrej Mizera, Jan Zelinka * 15/2172, 708 00 Ostrava,Czech Republic VSB-TUHruby, Ostrava, Faculty of Mechanical Engineering, 17. Čep listopadu Radek Lenka Cepova, Robert , Ondrej Mizera, Jan Zelinka
Abstract
VSB-TU Ostrava, Faculty of Mechanical Engineering, 17. listopadu 15/2172, 708 00 Ostrava,Czech Republic
The submitted article is dedicated to the detail comparison of measuring result of geometry optical element on light guide for car’s Abstract day light. Inspection and evaluation were performed on various measuring devices that use a different measurement principle. This article also describes the individual segments were prepared for measurement and the optical measurement Theguide obtained data The submitted article how is dedicated to the detail comparison of measuring result of geometry elementitself. on light for car’s are evaluated both from technical were pointperformed of view, where the actual measured values optical segments are compared day light. Inspection and aevaluation on various measuring devices that of usethe a different measurement principle. from This each measuring device, asthe wellindividual as from an economic point of view, the timeand intensity of the overall control of the optical article also describes how segments were prepared for where measurement the measurement itself. The obtained data elements is assessed. Based on the data obtained, has been the Atosvalues Core of optical scannersegments is best suited for measuring are evaluated both from a technical point of view,it where thefound actualthat measured the optical are compared from individual opticaldevice, segments. each measuring as well as from an economic point of view, where the time intensity of the overall control of the optical elements is assessed. Based on the data obtained, it has been found that the Atos Core optical scanner is best suited for measuring individual optical segments. © 2019 The Authors. Published by Elsevier B.V. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Modern and Safe (TRANSCOM 2019). © 2019 The Published by Elsevier B.V. Modern andAuthors. Safe Transport Transport (TRANSCOM 2019). Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Keywords: Measuring; Optical Segment; Light Guide; Optical Scanner; Coordinate Measuring Machine; Microscope Modern and Safe Transport (TRANSCOM 2019). Keywords: Measuring; Optical Segment; Light Guide; Optical Scanner; Coordinate Measuring Machine; Microscope
1. Introduction
1. Introduction The light guides are currently a frequent optical element used in the exterior or interior lighting of a vehicle where it is necessary to distribute the light from the light source so as to highlight important stylistic elements such as the The light guides currently frequent optical element usedthe in the exterior or interior lighting of a vehicle where contours around theare chambers ofathe individual light functions, outline of the whole lamp or lamp [1]. Skylights it is necessary to distribute the light from the lightlook source as to highlight stylistic elements such as the provide great opportunities to create an attractive forso headlights and areimportant important in vehicle interior lighting. contours the chambers individual lightcome functions, the outline of theforwhole lampwhen or lamp Skylights From the around stylish point of view, of thethe light-guide tubes in a variety of shapes, example, they[1]. surround the provide great opportunities to create an attractive look for headlights and are important in vehicle interior lighting. From the stylish point of view, the light-guide tubes come in a variety of shapes, for example, when they surround the *
Corresponding author E-mail address: [email protected]
* Corresponding author 2352-1465 © 2018 The Authors. Published by Elsevier B.V. E-mail address: [email protected] Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Modern and Safe Transport (TRANSCOM 2352-1465 © 2018 The Authors.2019). Published by Elsevier B.V.
Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Modern and Safe Transport (TRANSCOM 2019). 2352-1465 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Modern and Safe Transport (TRANSCOM 2019). 10.1016/j.trpro.2019.07.038
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chamber with other light functions, i.e. they create a contour of the headlamp or light, or fill and illuminate evenly a large part of the lamp [2]. The Best Fit mathematical method, which has been used on coordinate measuring machines for years, uses the probe to accurately position and rotate the workpiece to ideally match the CAD model [3]. For Best Fit, the Best Fit seeks the best match for the scanned and CAD model on selected (local) surfaces corresponding to the scanned and reference model [4]. The Best Fit method is based on the mathematical calculation of smallest squares [5]. For the smallest squares method, we require that the sum of the squares (second powers) of the difference values of the measured values and the real values from the CAD model for the same value was what smallest [6]. Dimensions and shapes are checked in the measuring room where the temperature is maintained 20 ± 1 ° C and constant relative humidity. Dimensional and shape parts should be stored for at least 24 hours after production in the measuring room prior to measurement [7]. 2. Current State of solved problems The largest customer of linear gauges is today mainly the automotive industry, which, together with the bearing industry, is the main driving force behind the development of a broad field of engineering metrology. In addition to purely technical issues related to the development of new progressive measurement methods, questions of philosophy and order in quality management are also preferentially addressed [8, 9]. In controlling the light-guide tubes serving the daytime running light function of the headlamps, the main factors determining the photometric output of the light guide are, in particular, the shape of the tooth-bundling system and the angle of the tooth with the longitudinal axis of the light guide [10]. Because of increasingly complex fiber optic shapes, which can hardly be clamped so as not to deform in the touch measurement, contactless gauges are increasingly used to control these parts. 2.1. Optical digital scanner Atos Core 185 The Atos Core (Fig. 1) is a 3D coordinate measuring system specially designed for small and medium-sized objects that use pioneering new technology and the scanner form the core for a wide range of measurement tasks such as 3D scanning, quality control, and fully automated measurement and inspection [11]. Radiant blue light is not so sensitive to ambient light when measured [12].
Fig. 1. Measuring system Atos Core 185 [11]
Table 1 Parameters of Atos Core 185 Measuring Area
185 x 140 mm
Working Distance
440 mm
Distance of Measured Points
0,07 mm
Sensor Size
361 x 205 x 64 mm
Radek Hruby et al. / Transportation Research Procedia 40 (2019) 251–258 Hruby et al. / Transportation Research Procedia 00 (2019) 000–000
253 3
2.2. Coordinating Measuring Machine Zeiss Contura G2 The Contura G2 (Fig. 2) Portal Coordinate Measurement Machine is a product of the German company Carl Zeiss. It is characterized by its high precision, flexibility and excellent resistance to environmental conditions [13]. The Contura G2 measuring machine provides cutting-edge performance for rapid and accurate measurement of complicated measurement tasks, thereby increasing measurement productivity [14]. Many aspects of the measurement strategy depend on the operator [15]. These are, for example: sensor configuration, sensor length, ball point diameter, sensor weight, or CMM working parameter [16].
Fig. 2. Coordinating Measuring Machine Zeiss Contura G2 with parameters [14] Table 2 Parameters of Measuring Machine Contura G2 Measuring Area
1000 x 1200 x 600 mm
Measuring Error
1,8 + L /350 um
Sensor Variant Touch probe diameter
VAST XT 0,5 mm
2.3. Digital microscope Keyence VHX 2000 It is a digital microscope (Fig. 3) that we can monitor, measure and record - all in a single system. This device is versatile, combining the capabilities of a conventional stereomicroscope, a measuring microscope, and a metallurgical microscope [17].
Fig. 3. Digital microscope Keyence VHX 2000 [17]
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Table 3 Parameters of digital microscope Keyence VHX 2000 Measuring Area
100 x 100 x 160 mm
Picture Calculating
D.F.D metoda
Objective Variant
VH-Z20W
Focus
20x to 200x
3. Experimental part In order to determine the corresponding geometry of the optical surfaces, three segments of the entire light guide are selected by the optical engineers to control important angles. It is mostly a segment that is at the beginning, at the middle and at the end of the light pipe (Fig. 4). If these segments are measured in tolerances, it is assumed that all other optical surfaces of the light guide are also within tolerances.
Fig. 4. Controlled optical segments
3.1. Comparison of the measurement preparation speed When comparing the speed of measurement preparation, it is important to mention that each measurement method has its own specifics. For an optical digital scanner, the workpiece must be shaken with titanium powder in the form of an aerosol and attached to the substrate on which the reference marks are not glued [18]. For a coordinate machine, the part must be secured with clamps so that it does not occur to the undesirable movement of the light guide during measurement and good access to the entire tooth geometry for touch point sensing must be ensured. When measuring on a digital microscope, the position of the light guide must be ensured so as to guarantee the perpendicularity of the optical segment to the lens. The measurement time savings of the measurement preparation was best done for the Atos Core 185 optical scanner. From table 4 it can be read that the time required for preparation of the measurement unit on the optical scanner will take 20 minutes, which is 2 minutes compared to 22 minutes for SMS Contura G2 compared to 25 minutes Keyence VHX digital microscope makes this saving for 5 minutes [19]. Table 4. Time savings associated with the speed of measurement preparation. Contura G2
Atos Core
Keyence
Part´s preparation [min]
2
15
10
Part´s set up [min]
20
5
15
Total [min]
22
20
25
3.2. Comparison of the speed of the measurement The evaluation of the speed of the measurement itself by the Atos Core 185 optical scanner takes into account the amount of time it takes to scan a sufficient surface area of the fiber optic segments and evaluate them. The better the optical surfaces are scanned, the more accurate it is and the results are evaluated [20]. For the measurement of optical segments by the Contura G2 coordinate machine, the time for which the technician must program the exact positions
Radek Hruby et al. / Transportation Research Procedia 40 (2019) 251–258 Hruby et al. / Transportation Research Procedia 00 (2019) 000–000
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of the balancing and measuring points, including their safety positions, is counted into the measurement speed. Keyence VHX 2000 Digital Velocity Measurement determines the length of time the operator enters individual geometric elements (lines, circles) and then evaluates the measured data. Evaluating the time savings of the measurement itself is best for the Atos Core 185 optical scanner. From Table 5 it can be seen that the time required to check the part on the optical scanner takes 22 minutes, which is 48 minutes compared to 70 minutes for SMS Contura G2 32 minutes on the Keyence VHX 2000 digital microscope makes this savings of 10 minutes [19]. Table 5. Time savings associated with measurement speed. Contura G2
Atos Core
Keyence
Measuring program create [min]
60
2
2
Measuring time [min]
10
20
30
Total [min]
70
22
32
3.3. Measurement evaluation options An important parameter for optical engineers who design the geometry of optical segments is how the measured values are evaluated. In general, here is the more information about the measured light guide is available, the better defects can be found that cause this work to fail. The Atos Core 185 optical scanner, after scanning the measured parts, can evaluate the results in various ways. The optical segment can be evaluated by a color map symbolizing the shape deviation from the nominal model at the specified tolerances. There is also the possibility of creating a section cut at different depths of the individual axes, giving a detailed overview of the shape of the cut (Fig. 5). Another way of presenting the results is the ability to extract the cut of the optical segment into a 2D image and the subsequent dimensioning [19]. a)
b)
Fig. 5. Measuring evaluation possibilities at optical scanner Atos Core 185
The Contura G2 coordinate measuring machine must touch the individual points to obtain the measured values. Subsequently, the current point coordinates compare to the nominal values and evaluate their deviations. These deviations are evaluated in the protocol where the individual points were scanned. It is also possible to obtain a plane through which at least three scraped points can be obtained, in which an angle can be evaluated with another focal plane (Fig. 6) [19].
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a)
b)
Fig. 6. Measuring evaluation possibilities at CMM Zeiss Contura G2
When evaluating the measured values by the Keyence VHX 2000 digital microscope, it is possible to refer to the 2D image dimensioning. Auxiliary elements are plotted on a scale obtained on a scale to determine the necessary data (Fig. 7) [19]. a)
b)
Fig. 7. Measuring evaluation possibilities at microscope Keyence VHX 2000
4. Experiment evaluation From a technical point of view, it is possible to measure the geometry of the fiber optic segments in different ways. These include non-contact optical scanning methods or digital microscopy, as well as contact metrics by coordinate machines. It can be seen from Table 6 that the measurement of the individual angles of the optical segment on all measuring machines has similar values. Table 6. Comparison of measured data. Segment 50
Segment 10
Segment -10
Angle 1 [°]
Angle 2 [°]
Angle 1 [°]
Angle 2 [°]
Angle 1 [°]
Angle 2 [°]
Contura G2
57.47
43.58
56.41
45.47
54.71
44.58
Atos Core 185
57.72
43.84
56.45
45.43
54.66
44.67
Keyence VHX
57.58
43.87
56.29
45.34
54.51
44.76
From the economic point of view, the speed of measuring preparation and the speed of measurement itself were assessed. From Table 7 it can be seen, that the Atos Core 185 optical scanner has the lowest time requirements for evaluating these criteria. The total time for measuring and evaluating the three optical segments by the optical scanner
Radek Hruby et al. / Transportation Research Procedia 40 (2019) 251–258 Hruby et al. / Transportation Research Procedia 00 (2019) 000–000
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is 42 minutes, which is a time saving of 15 minutes compared to the Keyence VHX 2000 digital microscope and 50 minutes against the Contura G2 coordinate machine. Table 7. Total time for preparation, measuring and evaluation of segments. Contura G2
Atos Core
Keyence
Part´s preparation [min]
2
15
10
Part´s set up [min]
20
5
15
Measuring program create [min]
60
2
2
Measuring time [min]
10
20
30
Total [min]
92
42
57
5. Conclusion The aim of the research was to find out how the optical fiber segments can be measured and evaluated. For comparison, deliberately different measuring devices were used, each device using a different measurement principle. The coordinate machine requires a firm clamping of the part and the use of a small diameter of the probe tip. The optical scanner must be tampered with titanium powder to ensure accuracy, and the microscope should have a perpendicular to the lens. After observing all these parameters, it can be said that the resulting values show little scattering, indicating the possibility of using the respective scoring devices to control the optical segments. This research continued to serve to determine the time requirements associated with the control of three selected fiber optic segments. From the measured velocity data of the measurement preparation, the velocity of the measurement itself and the subsequent evaluation of the measured values, it was found that the greatest time savings was obtained by an optical scanner. This saving was obtained especially when handling the work. While the coordinate machine has to be clamped so that it is not distorted and the microscope has to be perpendicular to the measuring lens, the scanner will simply attach the part to the point pad. Measuring small optical fiber optic segments will also play a significant role in future years when all exterior lighting of vehicles will be powered by LEDs. Thanks to these elements, individual car brands are recognizable at a glance. By changing, the materials from which the fiber optic cables are made are also undergoing. It is already contemplating manufacturers of headlamps over replacement of existing polycarbonate in the production of these elements as silicone. In terms of light guide control, we can say that these parts will need to be verified in the future in such a way that we can find out as much information as possible within a short time frame without damage. Here comes a series of measurements on CT devices. Acknowledgements Article has been done in connection with projects Education system for personal resource of development and research in field of modern trend of surface engineering - surface integrity, reg. no. CZ.1.07/2.3.00/20.0037 financed by Structural Founds of Europe Union and from the means of state budget of the Czech Republic and by project Students Grant Competition SP2018/136, SP2018/150 and SP2019/60 financed by the Ministry of Education, Youth and Sports and Faculty of Mechanical Engineering VŠB-TUO. References [1] Auto.cz [online]. History and future of car lighting: From candle to laser, February 2014. [cit. 26.4. 2017] Available at: http://www.auto.cz/historie-a-budoucnost-automobiloveho-osvetleni-od-svicky-k-laseru-79316. [2] Odborné časopisy [online]. Design of light pipes for automotive lighting, March 2013 [cit. 18. 4. 2017]. Available at: http://www.odbornecasopisy.cz/navrh-svetlovodu-pro-pouziti-v-automobilovemosvetleni-49711.html. [3] MM Průmyslové spektrum [online]. Measuring and checking molds and tools directly on a machine tool. September 2007 [cit. 26.4. 2017] Available at: http://www.mmspektrum.com/clanek/mereni-a-kontrola-forem-a-nastroju-primo-na-obrabecim-stroji.html
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[4] URBÁNEK P. Component Shape Inspection. [cit. 26.4. 2017] Available at: http://www.iae.fme.vutbr.cz/userfiles/ramik/files/Studium/Podklady%20ke%20studiu/3D%20skenování/E-learningInspekce%20tvaru%20soucasti.pdf. [5] ČEPOVÁ L, PETŘKOVSKÁ L: Legislativa ve strojírenské metrologie a přesné měření 3D ploch. [cit. 30. 4. 2017] Ostrava: VŠB – Technická univerzita Ostrava, Fakulta strojní, Katedra obrábění a montáže, 2011, 125 s. [6] ŘÍHOVÁ D. Aplikovaná matematika I. [cit. 28.4. 2017] Available at: http://user.mendelu.cz/qqrihova/zvm/PDF_soubory/prednasky/mnc.pdf. [7] Standard VDI/VDE 2627, Blatt 1, 1.12.2015 [8] MM Průmyslové spektrum [online]. Trends in the introduction of custom length gauges, June 2003 [cit. 18. 4. 2017]. Available at: http://www.mmspektrum.com/clanek/trendy-zavadeni-zakazkovych-delkovych-meridel.html. [9] TICHÁ Š. Strojírenská metrologie, část 1. [cit. 30. 4. 2017] Ostrava: VŠB – Technická univerzita Ostrava, Fakulta strojní, Katedra obrábění a montáže, 2004, 110 s. [10] MM Průmyslové spektrum [online]. Splinter defects - Part 2: Shape defects and dimensional defects, March 2010 [cit. 25.4. 2017]. Available at: http://www.mmspektrum.com/clanek/vady-vystriku-2-dil-vady-tvaru-a-rozmerove-vady.html. [11] MCAE, 3D digital technologies [online]. Atos Core, [cit. 19. 24 2017]. Available at: http://www.mcae.cz/atos-core. [12] Measurement [online]. 3D Optical Measuring Systems and Laser Technologies for Scientific and Industrial Applications, Number 1, 2001 [cit. 20. 4. 2017]. Available at: http://www.measurement.sk/2013/Chugui.pdf. [13] MM Průmyslové spektrum [online]. Currently measuring and control technique, March 2007 [cit. 20.4. 2017]. Available at: http://www.mmspektrum.com/clanek/ soucasna-merici-a-kontrolni-technika.html. [14] Zeiss [online]. Coordinating Measuring Machine Contura G2 [cit. 19. 24 2017]. Available at: http://www.zeiss.cz/imt. [15] TICHÁ Š. Strojírenská metrologie, část 2, Základy řízení jakosti. [cit. 2. 5. 2017] Ostrava: VŠB – Technická univerzita Ostrava, Fakulta strojní, Katedra obrábění a montáže, 2006, 86 s. [16] Measurement [online]. Optimisation Of Measuring Strategies in Coordinate Measuring Technique, Number 1, 2001 [cit. 20. 4. 2017]. Available at: http://www.measurement.sk/Papers2/Starczak.pdf . [17] Keyence, [online]. Digital microscope VHX 2000, [cit. 20. 24 2017]. Available at: http://www.keyence.com/products/microscope/digitalmicroscope/vhx2000/features/feature-08.jsp [18] KREMER PIGMENTE GMBH & CO. KG. 87099 - Cyclododecan Spray. Aichstetten, 2007, [cit. 23. 4. 2017] Available at: http://www.kremerpigmente.com/media/files_public/87099.pdf?xaf26a=cd72902c1470755ed01057f31711392e. [19] HRUBÝ, R. Measuring of Complex Small Parts: Diploma thesis. Ostrava: VŠB – TU Ostrava, Faculty of Mechanical Engineering, 2014, 60 p. Head: Vladimír Vrba. [20] Strojniśki vestnik - Journal of Mechanical Engineering [online]. Possibilities of Using Three-Dimensional Optical Scanning in Complex Geometrical Inspection. Vol. 57, 2011, No. 11, [cit. 23. 4. 2017]. Available at: http://en.svjme.eu/data/upload/2011/11/05_2010_152_Brajlih_05.pdf.
Available online at www.sciencedirect.com
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ScienceDirect
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Transportation Research Procedia 40 (2019) 251–258 www.elsevier.com/locate/procedia 13th International Scientific Conference on Sustainable, Modern and Safe Transport (TRANSCOM 2019), High Tatras, Novy Smokovec – Grand Hotel Bellevue, 13th International Scientific Conference Sustainable, Modern and Safe Transport Slovak Republic,on May 29-31, 2019 (TRANSCOM 2019), High Tatras, Novy Smokovec – Grand Hotel Bellevue, Slovak Republic, MayComplex 29-31, 2019 Shapes Measurement of Small
* Measurement ofRobert SmallČep Complex Shapes Radek Hruby, Lenka Cepova, , Ondrej Mizera, Jan Zelinka * 15/2172, 708 00 Ostrava,Czech Republic VSB-TUHruby, Ostrava, Faculty of Mechanical Engineering, 17. Čep listopadu Radek Lenka Cepova, Robert , Ondrej Mizera, Jan Zelinka
Abstract
VSB-TU Ostrava, Faculty of Mechanical Engineering, 17. listopadu 15/2172, 708 00 Ostrava,Czech Republic
The submitted article is dedicated to the detail comparison of measuring result of geometry optical element on light guide for car’s Abstract day light. Inspection and evaluation were performed on various measuring devices that use a different measurement principle. This article also describes the individual segments were prepared for measurement and the optical measurement Theguide obtained data The submitted article how is dedicated to the detail comparison of measuring result of geometry elementitself. on light for car’s are evaluated both from technical were pointperformed of view, where the actual measured values optical segments are compared day light. Inspection and aevaluation on various measuring devices that of usethe a different measurement principle. from This each measuring device, asthe wellindividual as from an economic point of view, the timeand intensity of the overall control of the optical article also describes how segments were prepared for where measurement the measurement itself. The obtained data elements is assessed. Based on the data obtained, has been the Atosvalues Core of optical scannersegments is best suited for measuring are evaluated both from a technical point of view,it where thefound actualthat measured the optical are compared from individual opticaldevice, segments. each measuring as well as from an economic point of view, where the time intensity of the overall control of the optical elements is assessed. Based on the data obtained, it has been found that the Atos Core optical scanner is best suited for measuring individual optical segments. © 2019 The Authors. Published by Elsevier B.V. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Modern and Safe (TRANSCOM 2019). © 2019 The Published by Elsevier B.V. Modern andAuthors. Safe Transport Transport (TRANSCOM 2019). Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Keywords: Measuring; Optical Segment; Light Guide; Optical Scanner; Coordinate Measuring Machine; Microscope Modern and Safe Transport (TRANSCOM 2019). Keywords: Measuring; Optical Segment; Light Guide; Optical Scanner; Coordinate Measuring Machine; Microscope
1. Introduction
1. Introduction The light guides are currently a frequent optical element used in the exterior or interior lighting of a vehicle where it is necessary to distribute the light from the light source so as to highlight important stylistic elements such as the The light guides currently frequent optical element usedthe in the exterior or interior lighting of a vehicle where contours around theare chambers ofathe individual light functions, outline of the whole lamp or lamp [1]. Skylights it is necessary to distribute the light from the lightlook source as to highlight stylistic elements such as the provide great opportunities to create an attractive forso headlights and areimportant important in vehicle interior lighting. contours the chambers individual lightcome functions, the outline of theforwhole lampwhen or lamp Skylights From the around stylish point of view, of thethe light-guide tubes in a variety of shapes, example, they[1]. surround the provide great opportunities to create an attractive look for headlights and are important in vehicle interior lighting. From the stylish point of view, the light-guide tubes come in a variety of shapes, for example, when they surround the *
Corresponding author E-mail address: [email protected]
* Corresponding author 2352-1465 © 2018 The Authors. Published by Elsevier B.V. E-mail address: [email protected] Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Modern and Safe Transport (TRANSCOM 2352-1465 © 2018 The Authors.2019). Published by Elsevier B.V.
Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Modern and Safe Transport (TRANSCOM 2019). 2352-1465 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 13th International Scientific Conference on Sustainable, Modern and Safe Transport (TRANSCOM 2019). 10.1016/j.trpro.2019.07.038
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Radek Hruby et al. / Transportation Research Procedia 40 (2019) 251–258 Hruby et al. / Transportation Research Procedia 00 (2019) 000–000
chamber with other light functions, i.e. they create a contour of the headlamp or light, or fill and illuminate evenly a large part of the lamp [2]. The Best Fit mathematical method, which has been used on coordinate measuring machines for years, uses the probe to accurately position and rotate the workpiece to ideally match the CAD model [3]. For Best Fit, the Best Fit seeks the best match for the scanned and CAD model on selected (local) surfaces corresponding to the scanned and reference model [4]. The Best Fit method is based on the mathematical calculation of smallest squares [5]. For the smallest squares method, we require that the sum of the squares (second powers) of the difference values of the measured values and the real values from the CAD model for the same value was what smallest [6]. Dimensions and shapes are checked in the measuring room where the temperature is maintained 20 ± 1 ° C and constant relative humidity. Dimensional and shape parts should be stored for at least 24 hours after production in the measuring room prior to measurement [7]. 2. Current State of solved problems The largest customer of linear gauges is today mainly the automotive industry, which, together with the bearing industry, is the main driving force behind the development of a broad field of engineering metrology. In addition to purely technical issues related to the development of new progressive measurement methods, questions of philosophy and order in quality management are also preferentially addressed [8, 9]. In controlling the light-guide tubes serving the daytime running light function of the headlamps, the main factors determining the photometric output of the light guide are, in particular, the shape of the tooth-bundling system and the angle of the tooth with the longitudinal axis of the light guide [10]. Because of increasingly complex fiber optic shapes, which can hardly be clamped so as not to deform in the touch measurement, contactless gauges are increasingly used to control these parts. 2.1. Optical digital scanner Atos Core 185 The Atos Core (Fig. 1) is a 3D coordinate measuring system specially designed for small and medium-sized objects that use pioneering new technology and the scanner form the core for a wide range of measurement tasks such as 3D scanning, quality control, and fully automated measurement and inspection [11]. Radiant blue light is not so sensitive to ambient light when measured [12].
Fig. 1. Measuring system Atos Core 185 [11]
Table 1 Parameters of Atos Core 185 Measuring Area
185 x 140 mm
Working Distance
440 mm
Distance of Measured Points
0,07 mm
Sensor Size
361 x 205 x 64 mm
Radek Hruby et al. / Transportation Research Procedia 40 (2019) 251–258 Hruby et al. / Transportation Research Procedia 00 (2019) 000–000
253 3
2.2. Coordinating Measuring Machine Zeiss Contura G2 The Contura G2 (Fig. 2) Portal Coordinate Measurement Machine is a product of the German company Carl Zeiss. It is characterized by its high precision, flexibility and excellent resistance to environmental conditions [13]. The Contura G2 measuring machine provides cutting-edge performance for rapid and accurate measurement of complicated measurement tasks, thereby increasing measurement productivity [14]. Many aspects of the measurement strategy depend on the operator [15]. These are, for example: sensor configuration, sensor length, ball point diameter, sensor weight, or CMM working parameter [16].
Fig. 2. Coordinating Measuring Machine Zeiss Contura G2 with parameters [14] Table 2 Parameters of Measuring Machine Contura G2 Measuring Area
1000 x 1200 x 600 mm
Measuring Error
1,8 + L /350 um
Sensor Variant Touch probe diameter
VAST XT 0,5 mm
2.3. Digital microscope Keyence VHX 2000 It is a digital microscope (Fig. 3) that we can monitor, measure and record - all in a single system. This device is versatile, combining the capabilities of a conventional stereomicroscope, a measuring microscope, and a metallurgical microscope [17].
Fig. 3. Digital microscope Keyence VHX 2000 [17]
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Table 3 Parameters of digital microscope Keyence VHX 2000 Measuring Area
100 x 100 x 160 mm
Picture Calculating
D.F.D metoda
Objective Variant
VH-Z20W
Focus
20x to 200x
3. Experimental part In order to determine the corresponding geometry of the optical surfaces, three segments of the entire light guide are selected by the optical engineers to control important angles. It is mostly a segment that is at the beginning, at the middle and at the end of the light pipe (Fig. 4). If these segments are measured in tolerances, it is assumed that all other optical surfaces of the light guide are also within tolerances.
Fig. 4. Controlled optical segments
3.1. Comparison of the measurement preparation speed When comparing the speed of measurement preparation, it is important to mention that each measurement method has its own specifics. For an optical digital scanner, the workpiece must be shaken with titanium powder in the form of an aerosol and attached to the substrate on which the reference marks are not glued [18]. For a coordinate machine, the part must be secured with clamps so that it does not occur to the undesirable movement of the light guide during measurement and good access to the entire tooth geometry for touch point sensing must be ensured. When measuring on a digital microscope, the position of the light guide must be ensured so as to guarantee the perpendicularity of the optical segment to the lens. The measurement time savings of the measurement preparation was best done for the Atos Core 185 optical scanner. From table 4 it can be read that the time required for preparation of the measurement unit on the optical scanner will take 20 minutes, which is 2 minutes compared to 22 minutes for SMS Contura G2 compared to 25 minutes Keyence VHX digital microscope makes this saving for 5 minutes [19]. Table 4. Time savings associated with the speed of measurement preparation. Contura G2
Atos Core
Keyence
Part´s preparation [min]
2
15
10
Part´s set up [min]
20
5
15
Total [min]
22
20
25
3.2. Comparison of the speed of the measurement The evaluation of the speed of the measurement itself by the Atos Core 185 optical scanner takes into account the amount of time it takes to scan a sufficient surface area of the fiber optic segments and evaluate them. The better the optical surfaces are scanned, the more accurate it is and the results are evaluated [20]. For the measurement of optical segments by the Contura G2 coordinate machine, the time for which the technician must program the exact positions
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of the balancing and measuring points, including their safety positions, is counted into the measurement speed. Keyence VHX 2000 Digital Velocity Measurement determines the length of time the operator enters individual geometric elements (lines, circles) and then evaluates the measured data. Evaluating the time savings of the measurement itself is best for the Atos Core 185 optical scanner. From Table 5 it can be seen that the time required to check the part on the optical scanner takes 22 minutes, which is 48 minutes compared to 70 minutes for SMS Contura G2 32 minutes on the Keyence VHX 2000 digital microscope makes this savings of 10 minutes [19]. Table 5. Time savings associated with measurement speed. Contura G2
Atos Core
Keyence
Measuring program create [min]
60
2
2
Measuring time [min]
10
20
30
Total [min]
70
22
32
3.3. Measurement evaluation options An important parameter for optical engineers who design the geometry of optical segments is how the measured values are evaluated. In general, here is the more information about the measured light guide is available, the better defects can be found that cause this work to fail. The Atos Core 185 optical scanner, after scanning the measured parts, can evaluate the results in various ways. The optical segment can be evaluated by a color map symbolizing the shape deviation from the nominal model at the specified tolerances. There is also the possibility of creating a section cut at different depths of the individual axes, giving a detailed overview of the shape of the cut (Fig. 5). Another way of presenting the results is the ability to extract the cut of the optical segment into a 2D image and the subsequent dimensioning [19]. a)
b)
Fig. 5. Measuring evaluation possibilities at optical scanner Atos Core 185
The Contura G2 coordinate measuring machine must touch the individual points to obtain the measured values. Subsequently, the current point coordinates compare to the nominal values and evaluate their deviations. These deviations are evaluated in the protocol where the individual points were scanned. It is also possible to obtain a plane through which at least three scraped points can be obtained, in which an angle can be evaluated with another focal plane (Fig. 6) [19].
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a)
b)
Fig. 6. Measuring evaluation possibilities at CMM Zeiss Contura G2
When evaluating the measured values by the Keyence VHX 2000 digital microscope, it is possible to refer to the 2D image dimensioning. Auxiliary elements are plotted on a scale obtained on a scale to determine the necessary data (Fig. 7) [19]. a)
b)
Fig. 7. Measuring evaluation possibilities at microscope Keyence VHX 2000
4. Experiment evaluation From a technical point of view, it is possible to measure the geometry of the fiber optic segments in different ways. These include non-contact optical scanning methods or digital microscopy, as well as contact metrics by coordinate machines. It can be seen from Table 6 that the measurement of the individual angles of the optical segment on all measuring machines has similar values. Table 6. Comparison of measured data. Segment 50
Segment 10
Segment -10
Angle 1 [°]
Angle 2 [°]
Angle 1 [°]
Angle 2 [°]
Angle 1 [°]
Angle 2 [°]
Contura G2
57.47
43.58
56.41
45.47
54.71
44.58
Atos Core 185
57.72
43.84
56.45
45.43
54.66
44.67
Keyence VHX
57.58
43.87
56.29
45.34
54.51
44.76
From the economic point of view, the speed of measuring preparation and the speed of measurement itself were assessed. From Table 7 it can be seen, that the Atos Core 185 optical scanner has the lowest time requirements for evaluating these criteria. The total time for measuring and evaluating the three optical segments by the optical scanner
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is 42 minutes, which is a time saving of 15 minutes compared to the Keyence VHX 2000 digital microscope and 50 minutes against the Contura G2 coordinate machine. Table 7. Total time for preparation, measuring and evaluation of segments. Contura G2
Atos Core
Keyence
Part´s preparation [min]
2
15
10
Part´s set up [min]
20
5
15
Measuring program create [min]
60
2
2
Measuring time [min]
10
20
30
Total [min]
92
42
57
5. Conclusion The aim of the research was to find out how the optical fiber segments can be measured and evaluated. For comparison, deliberately different measuring devices were used, each device using a different measurement principle. The coordinate machine requires a firm clamping of the part and the use of a small diameter of the probe tip. The optical scanner must be tampered with titanium powder to ensure accuracy, and the microscope should have a perpendicular to the lens. After observing all these parameters, it can be said that the resulting values show little scattering, indicating the possibility of using the respective scoring devices to control the optical segments. This research continued to serve to determine the time requirements associated with the control of three selected fiber optic segments. From the measured velocity data of the measurement preparation, the velocity of the measurement itself and the subsequent evaluation of the measured values, it was found that the greatest time savings was obtained by an optical scanner. This saving was obtained especially when handling the work. While the coordinate machine has to be clamped so that it is not distorted and the microscope has to be perpendicular to the measuring lens, the scanner will simply attach the part to the point pad. Measuring small optical fiber optic segments will also play a significant role in future years when all exterior lighting of vehicles will be powered by LEDs. Thanks to these elements, individual car brands are recognizable at a glance. By changing, the materials from which the fiber optic cables are made are also undergoing. It is already contemplating manufacturers of headlamps over replacement of existing polycarbonate in the production of these elements as silicone. In terms of light guide control, we can say that these parts will need to be verified in the future in such a way that we can find out as much information as possible within a short time frame without damage. Here comes a series of measurements on CT devices. Acknowledgements Article has been done in connection with projects Education system for personal resource of development and research in field of modern trend of surface engineering - surface integrity, reg. no. CZ.1.07/2.3.00/20.0037 financed by Structural Founds of Europe Union and from the means of state budget of the Czech Republic and by project Students Grant Competition SP2018/136, SP2018/150 and SP2019/60 financed by the Ministry of Education, Youth and Sports and Faculty of Mechanical Engineering VŠB-TUO. References [1] Auto.cz [online]. History and future of car lighting: From candle to laser, February 2014. [cit. 26.4. 2017] Available at: http://www.auto.cz/historie-a-budoucnost-automobiloveho-osvetleni-od-svicky-k-laseru-79316. [2] Odborné časopisy [online]. Design of light pipes for automotive lighting, March 2013 [cit. 18. 4. 2017]. Available at: http://www.odbornecasopisy.cz/navrh-svetlovodu-pro-pouziti-v-automobilovemosvetleni-49711.html. [3] MM Průmyslové spektrum [online]. Measuring and checking molds and tools directly on a machine tool. September 2007 [cit. 26.4. 2017] Available at: http://www.mmspektrum.com/clanek/mereni-a-kontrola-forem-a-nastroju-primo-na-obrabecim-stroji.html
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